Most of us bear at least some passing knowledge of classics like Oliver Twist, Great Expectations or that seasonal standby, A Christmas Carol. But how much do we know about the genius who created them?

In The Invisible Woman, opening on Dec. 25, Ralph Fiennes sets about turning Charles Dickens -- who over the centuries has calcified into more of a literary brand-name than anything else -- into a flesh-and-blood figure grappling with all-too-human problems. Fiennes' sophomore directorial effort, in which he also stars, is based on a 1990 biography by Claire Tomalin, and details a scandalous chapter in the author's life, when, at the height of his fame, he fell under the spell of an 18-year-old beauty named Nelly Wharton (played in the film by Felicity Jones).

With her sisters and mother (portrayed by Fiennes' good friend and English Patient co-star Kristin Scott Thomas),Nelly leads a very modest existence as part of a troupe of touring actresses, and the financial stability Dickens' attentions would bring them could change their lives forever. But there's a problem, as Dickens -- depicted here as a ferociously talented force of nature as well as something of a self-serving brute -- is still married to wife Catherine, who bore him 10 children, but in whom his interest has steadily dwindled over the years.

"He couldn't just be with Nelly," Fiennes explains during a recent sit-down with The Hollywood Reporterat the Chateau Marmont. "He would have had to divorce his wife, and the circumstances of the divorce would have forced him to make his personal dealings public." The pair eventually give in to their mutual attraction, but Dickens, submissive to a fault to Victorian-era mores, doggedly refuses to allow their communion to ever go public, rendering Nelly the "invisible woman" of the title.

The lengths to which Dickens goes to hide their love away can be startling. In one scene, Dickens destroys all of his written correspondences -- what amount to hundreds and hundreds of letters -- lest they contain proof that his love for Nelly was real. His behavior later grows even more unforgivable: During a rail accident that occurs while the couple is mourning the recent death of a newborn, the author, panicked that they might be found together, leaves Nelly in the care of strangers.

All of it is based on historical fact, Fiennes says, who admits that he knew little of Dickens' personal life before tackling the project. "I didn't know he was such a contradictory, difficult, brilliant, furiously engaged, controlling father and maniacal worker. There were so many things about him that were brilliant, and I love it when people are very contradictory." Fiennes nevertheless found himself sympathizing with his character. "I think he's not a bad guy," he reasons. "He's capable of being very cruel, very controlling, yes. But the whole profile is that of a man capable of huge acts of social generosity." It's that push and pull between protagonist and audience that serves to elevate The Invisible Woman above rote period dramas, leading THR chief film critic Todd McCarthy to declare it "a career high-point" for the 50-year-old actor-director.

Then again, Fiennes has always excelled at mining his characters' dark sides. Twenty years prior, he rocketed to international attention after being hand-picked by Steven Spielberg to appear in his landmark Holocaust drama, Schindler's List, as Amon Goeth, the Nazi concentration camp commandant who shot prisoners for sport. The part, which earned him the first of two Oscar nominations, is one that will stick with him for a lifetime.

"To be with a group of actors, a crew, all feeling that Steven was sort of messianic in his determination to tell a story with truth, reality -- it was very, very, very potent," Fiennes recalls of the shoot. "The drivenness of Steven on it was really extraordinary." (Asked what he thought of this year's 12 Years a Slave, another difficult film depicting historical atrocities, he says it "really disturbed me. It really upset me. So I felt very eviscerated by it -- the cruelty depicted in it was painful.")

Fiennes says he was happy to close the book -- or make that seven books -- on the Harry Potter series' Lord Voldemort ("The grand finale was great, but I'm happy it's a completed thing," he says). Next, he'll lighten things up playing Gustave H., the spinster-wooing concierge at the center of Wes Anderson's upcoming The Grand Budapest Hotel, which opens on March 7.

Farther out on the horizon, yet another blockbuster franchise awaits, as he takes over as M from the departing Judi Dench in the next James Bond installment. Fiennes says he has no idea what to expect from Bond 24, which begins shooting in October for a fall 2015 release, but with director Sam Mendes back after helming 2012's Skyfall, in which Fiennes made his 007 debut, he can't wait to get started: "With Sam on the set, things like motivation and what's going on inside your head are part of the conversation."